I tried it maybe 2 years ago. I signed in a month later and noticed there was a vendor button (or something like it) where it listed my name and address in public location for everybody to see, along with that of all other users. I think it was a list of "vendors" (ie, to buy from other thinkcomp users.) The page was white. There was no way to disable it. I ended up e-mailing somebody to remove my name from the list.

I'm not sure that it beats QuickBooks, even though I haven't tried either product recently. And I wouldn't worry about Facebook.

This isn't an entirely fair criticism. The section you are talking about was labeled "Marketplace," and it was intended to be a way for users of the software to find other companies to either network with or buy/sell from/to. It was completely independent of the "Vendors" section and had no bearing on the accounting aspects of the software. The feature has since been removed, in any case, since I didn't have enough time to work on it.

Why did this fail? Also, "Inventors of The Facebook"?

"The Facebook" was the original name of the site. thefacebook.com still links to it, actually.

Mostly because people don't know about it I think. And yes, that would be true.